Punch press guard



y 1933. E. D. HOWELL 1,918,037

PUNCH PRES S GUARD Filed May 19, 1928 3 Sheets-Sheet 1 IV ENTOR A m/m0flQ/Voh/HL.

ATTOR E July 11, 1933; E D HOWELL PUNCH PRESS GUARD Filed May 19, 1928 3Sheets-Sheet 2 lNVENTOR TTORNE July 11, 1933. D E L PUNCH PRES S GUARDFiled May 19, 1928 3 Sheets-Sheet 3 INVENTOR gwvn/m Q Hon/ELL MTORNEY. i

Patented July 11, 1933 UNITED STATES r ."r ,rricn.

EDWARD D. HOWELL, 0F SPRINGFIELD GARDENS, ZNEVI" YORK, ASSIGNOR, BYASSIGNMENTS, TO SPERRY GYROSCOPE COMPANY, INC 015 BROOKLYN, NEW YORK, A

CORPORATION OF NEW YORK PUNCH PRESS GUARD 7 Application filed May 19,1928. Serial No. 279,091.

My invention relates to safety devices on power machines and isparticularly designed in this case to guard the hands of the operator ofa power press. The object of such a guard is to make it impossible forthe opera tor to put his hands beneath the operating ram of such amachine. V 7

Accident records show that more injuries occur on power presses orpunches than on any other machine, with perhaps one eXception,-thecircular saw. In practically all press accidents the operators fingersare caught under the ram at the point of operation. This is due to (1)the press repeating, (2) the operator leaving hishand beneath the diesas the ram descends, or an unexpected stroke caused by accidentaltripping of the treadle which serves to connect the ram to the powershaft.

One of the objects of my invention is the provision of a suitable guard,which when in effective position will prevent access by the operator tothe operating element of the machine.

A further object of my invention is the provision of means wherebyoperation of the machine is prevented until the guard has been moved toeffective position, thus pre venting accidental operation of themachine.

A further object of my invention is the provision of a guard of the typedescribed, which may be actuated to effective and ineffective positionsand which may be readily removed from. the machine if desired to permitcertain classes of work, with which it might otherwise interfere, to beperformed- Another object of my invention is the pro vision of a guardof the type described, which is adjustable to accommodate itself to workof various thicknesses and shapes.

In the accompanying; drawings in' which I have shown what I nowconsiderto be the preferred form of the invention,

Fig. 1 is a front view of my invention applied to a power punch press.

Fig. 2 is an end view of the Fig. 1 device.

Fig. 3 is a View of a portion of the end opposite to that of. Fig. 2;

Fig. a is a view of another portion of the same end as Fig. 3, showingthe power-operating shaft and the trigger for releasing the same.

Fig. 5 is a view similar to Fig. 4 showing.

a modified form of trigger control.

Fig. 6 is a front elevation of the guard or safety device on a largerscale than Fig. 1,

parts being removed for clearness.

Fig: 7 is a detail showing the/same parts as 2 but with the operatinghandle in a different position. I

I have illustrated my invention as applied to a power punch press butit'will be clear from the following description that it is capable of amuch broader application than the one illustrated. Asshown, the guardisapplied to the usual power punch press comprising the heavyl'ip-ri 'htframe 5 support ing a- Crank shaft 6, having the usual power wheel 7.The crank shaft has suitably mounted thereon for reciprocatory movementa ram 8 adapted to have secured-thereto one member of the die 9, whichis adapted to cooperate with the other member 10 of the die secured to aplatform or baseplate 11' of themachine. The usual. trip lever treadle12 is provided for operating the trigger 13 of the machine throughconnecting rods 14 whereby release of the trigger serves to clut litheshaft 6 to the power drive 7 to operate the punch or rain.

The safety guard which I provide may be secured to the stationary frame5 bymeans of a suitable bracket 15 supporting a shaft 16 to telescopewithin the arms and be locked therein in any suitable manner so as toallow the swingingguard frame 23, carried by said extensions, to covercompletely the front of the lower die so' as to prevent the operatorfrom putting his hands beneath the die or to permit the swinging frameto be raised to accommodate work of varying thickness and shape whichprojects outwardlybeneath said frame. The extensions 21 and 22 fit oversuitable pins in the swing guard v23 and a spring member 2 holds themsecure tosaid frame so that should it be desired to remove the guard itis only necessary to withdraw the said spring member.

The guard is normally held inthe ineffectlve position shown in fulllines in Fig; 1.

' and in dotted lines in Fig. 6 byimeans such as a spring 32 fastened toface plate 17 and. en-.

gaging one of the supporting arms, 131111131 adapted to be moved to theeffective position shown in dotted lines in Fig. 1 and in full line inFig. 6. The means for operating the guard to effective position maycomprise the shaft 16 to. which is secured hand-operated levers 25 and26 on each end of the shaft to permit operation by either hand. One ofsaid levers, such as 25, may be provided with a cam finger 27 (see Figs.2 and 7 adapted to extend forwardly and engage a locking lever 28pivoted upon plate 17. Said lever 28 may be provided with two arms 29and 30, the latter having a link 31 connecting it to one of theswingingarms (here shown as arm 18), whereby said arms 18 and 19 and theguard 23 may be operated to effective position against the pressure ofspring 32 which normally tends to maintain said guard in ineffectiveposition.

As hereinbefore stated, it is one of the principal objects of myinvention to prevent operation of the ram or punch unless or until theguard is in its effective position. To accomplish this ob ect, I providea locklng means 40 in the form of a lun er normall pressed by a spring41 into engagement with the lower side of trigger 13 to prevent releaseof said trigger when the operator steps upon the treadle 12 and drawsdown upon link 14. It willbe understood that the trigger normally abutsagainst the spring clutch member 52 on the crank shaft 6 and thusreleases the shaft from the power wheel 7, but that as soon as thetrigger is released from engagement with said member 52, the shaft 6 isconnected to the power wheel and the ram or punch is operated. It willbe understood that the spring 52 is normally maintained compressed bythe rotation of the flywheel 7 with which the collar 152 has frictionalengagement, and that as soon as the member 52 is released by the catch13, spring 52 forces the catch forwardly, rotating the same and bringinga tooth thereon (not shown) into engagement with internal teeth (notshown) on the hub 7 of the flywheel. Such clutches are well known in theart and need not be further described. By providing the detent 40, Itake the initial control of said clutch mechanism away from the treadle12 and by connecting said detent 40 with the guard mechanism make thefunctioning of the clutch mechanism dependent upon the operation of theguard mechanism. For this purpose I have shown upon, shaft 16 an armwhich fits into a slot 39 in the outer end of detent member 40 so thatwhen handle 25 or 26 is operated to move the guard to its effectivepoistion the said arm 33 will be rocked and the detent 40 moved fromunder the trigger 13 until the point where the guard has reached itseffective position, whereupon detent 40 will disengage trigger 13 topermit said trigger-to be actuated by operation of the treadle. Thus itwill be seen that not until the guard has reached its effective positioncan the operator cause actuation of the press by stepping upon thetreadle. Accidental operation of the press without the guard mechanismbeing in protective position. is thus rendered impossible. V a

In Fig. 5, I have disclosed a modified form of detent for preventingactuation of the trigger 13 by the treadle mechanism. In this form,instead of a spring pressed detent, I preferto employ a detent 40, whichis one end of a bell crank 53, the otherarm 54 of which is weighted soas normally to main; tain the detent in looking position. The operationof the Fig. 5 form is in other respects the same as in the Fig. 4 formof the invention. In both forms the trigger is shown as operatingbetween an upper limit stop 49 and a lower stop 50, the latter of whichmay be in the form of an adjusting screw 51 whereby to adjust the limitof downward movement.

For certaintypes of work continuous operation of the punch press isdesirable and, therefore, I provide means whereby the guard may bemaintained in its lowermost or effective position without the operatorpressing down handles 25 and 26. For this purpose the lever carrying oneof said handles, such as handle 25, may be provided at its opposite endwith a nose or cam 34 which cooperates with a cam lever 35 having a handle 36, which when operated downwardly to its lower positions, as shownin dotted lines in Fig. 2, or in full lines in Fig. 7 will cause thenose 34 to ride up on the face of cam 35 and thus operate guard 23 tolowermost position where it is maintained until handle 36 is raised.

In accordance with the provisions of the patent statutes, I have hereindescribed the principle and operation of my invention, together withtheapparatus which I now consider to represent the best embodiment thereof,but I desire to have it understood that the apparatus shown is onlyillustrative and that the invention can be carried out by other means.Also, while it is designed to use the various features and elements inthe combination and relations described, some of these may be alteredand others omitted without interfering with the more general results oulined, and the invention extends to such use. Having described myinvention, what I claim and desire to secure by Letters Patent is:

1. In an attachment for-machine tools having a driving shaft, anoperating. member,

7 means including a trigger whereby said memsaid hard in inefiective)osition and means actuated by the movement of said guard into effectiveposition for rendering said lastnamed means inoperative to permitrelease of said trigger by the operator.

' movable to effective and ineffective positions,

means normally maintaining said guard in ineifective position, and meansactuated by the movement of said guard into effective position forrendering said trigger releasepreventing means inoperative to permitrelease of said trigger by said treadle.

3. An attachment for machine tools having a driving shaft, an operatingmember, and means including a trigger whereby said member may beconnected to said shaft, comarising a guard for preventing access tosaid member by an operator, means for moving said guard to effective andineffective positions, a wedge adapted to engage under said trigger toprevent release thereof, means whereby said wedge normally lockssaidtrigger, and means whereby said guard operating means releases saidwedge to disengage the same when said guard is moved to efiectiveposition.

f. A power punch or the like having a driving shaft, a work-engagingmember, means including a trigger whereby said member may be connectedto said shaft, a guard for preventing access to said member by anoperator, means for moving said guard to effective position, meansnormally maintaining said guard in ineffective position, a locking meansnormally engaging said trig- I ger to prevent its release, and a handleto move said guard to its operative position to release said lockingmeans thereby permitting said trigger to be operated by the normal punchoperating mechanism only when the guard is in the effective position.

5. In combination, a. machine having a driving shaft, an operatingmember, means including a trigger whereby said member may be connectedto said shaft, springpressed means normally maintaining said trigger inposition to prevent said connection, a guard for preventing access tosaid member by an operator means for moving said guard to effective andineffective positions, locking means directly engaging said triggerwhereby release of said trigger is prevented if said springpressed meansfails, and means whereby said guard operating means actuates saidlocking means to disengage the same from said trigger when said guard ismoved to effective position.

6. In combination, a machine having a driving shaft, an operatingmember, means including a trigger whereby said member may be connectedto said shaft, springpressed means normally maintaining said trigger inposition to prevent said connection, a guard for preventing access tosaid member by an operator means for moving said guard to effective andineffective positions, locking means directly engaging said trigger andinterposed between said trigger and said spring-pressed means wherebyrelease of said trigger is prevented if said springpressed means fails,and means whereby said guard operating means actuates said locking meansto disengage the same from said trigger when said guard is moved toeffective position.

7. A power punch or the like having a driving shaft and a work-engagingmember, means including a trigger whereby said member may be connectedto said shaft, a treadle adapted to be actuated by the operator forreleasing said trigger, a lock normally preventing release of saidtrigger by said treadle, and a handle adjacent the work for temporarilyreleasing said lock whereby said means is only operated when both saidhandle and treadle are operated.

8. A power punch or the like having a driving shaft and a work-engagingmember,

'means including a trigger whereby said member may be connected to saidshaft, a treadle adapted to be actuated by the operator for releasingsaid trigger, a lock normally preventing release of said trigger by saidtreadle, a handle adjacent the work for temporarily releasing said lockwhereby said means is only operated when both said handle and treadleare operated, and means for locking said handle down for continuousoperation through the treadle.

9. A power punch or the like having a driving shaft and a work-engagingmember, means whereby said membe may be connected to said shaft, a guardfor preventing access to said member by an operator, means for pivotingthe guard above the work whereby it may be swung to one side of andabove the work in its ineffective position, means for normallymaintaining said guard in such ineffective position, manual means formoving said guard to effective position, and means whereby saidfirst-named means is maintained inoperative until said guard is in itseffective position.

In testimony whereof I have aiiixed by signature.

EDWARD D. HOWELL.

